In human beings, the frontal paranasal sinuses reside on either side of the forehead adjacent to and above the orbits. The right and left frontal sinuses are divided by an intersinus septum. Each frontal sinus has a natural opening (i.e., an ostium) formed in the posteromedial aspect of the sinus floor. In most patients, a narrow anatomical pre-chamber known as the frontal recess extends between the frontal sinus ostium and the nasal cavity. The frontal recess is a bony structure covered by mucosal tissue. The anterior border of the frontal recess is formed by the posterior wall of the agger nasi cell and the medial aspect of the frontal recess relates to the lateral lamella of the cribriform and the cribriform plate. Mucous normally drains out of the frontal sinus ostium, through the frontal recess, and into the nasal cavity. The ostium and frontal recess are sometimes referred to in combination as the frontal outflow tract (FOT). In many individuals, the FOT is a relatively long passage.
In patients suffering from acute frontal sinusitis, the FOT may become inflamed and occluded, thereby impeding natural drainage from the frontal sinus cavity and allowing infectious organisms to thrive within the frontal sinus cavity and associated ethmoid air cells. Acute frontal sinusitis is sometimes associated with intracranial and/or ocular complications. Ocular complications that are known to result from frontal sinusitis include thrombosis, thrombophlebitis, cellulites and orbital abscesses. One type of orbital abscess, known as a Pott puffy tumor, is associated with considerable soft tissue swelling over the frontal bone. Intracranial complications associated with frontal sinusitis include meningitis, brain abscess, epidural empyema, subdural empyema, and cerebral empyema.
In current practice, surgical procedures are performed for the treatment of acute frontal sinusitis only after the condition has failed to respond to conservative therapy (e.g., administration of antibiotics and mucolytic agents along with topical steroids and topical or systemic decongestants) or when other complications are present or when the infection has recurred more than 3-4 times in a year. The surgical procedures used to treat acute frontal sinusitis include functional endoscopic sinus surgery (FESS) procedures as well as open surgical procedures.
In FESS procedures, a nasal endoscope and other instruments (e.g., seekers, probes, rongeurs, a drills, and bony curettes) are inserted transnasally and used to improve patency of the FOT or otherwise improve drainage from the diseased frontal sinus. This process often involves the performace of an uncinectomy, anterior ethmoidectomy, agger nasi removal, and/or resection of the anterosuperior attachment of the middle turbinate. In some cases, the superior aspect of the nasal septum may be removed in a bilateral frontal sinus drill-out procedure. In many frontal sinus FESS procedures, disease of the anterior ethmoids is also be addressed during the surgery. In some cases, a stent is placed within the surgically altered FOT to maintain its patency in the weeks following the surgery. In cases where a stent is implanted, the patient is typically advised to irrigate the stent several times a day for up to 5-7 weeks after the surgery.
Postoperatively, it is typically necessary for FESS patients to visit the surgeon periodically for postoperative care, such as debridement, removal of clots, removal of granulation tissue, removal of crust, removal of polyps, etc.
FESS treatment of frontal sinusitis does have some disadvantages. For example, the FESS procedures are technically complex, accessing disease in the supraorbital frontal sinus cell is difficult, postoperative care can be laborious, confirming the patency of the surgically altered FOT may be difficult during the initial postoperative period.
Moreover, given the risks associated with the FESS procedure, some patients with relatively mild frontal sinusitis are not considered to be candidates for the procedure even though the available medical therapies may provide them with less than complete relief.
In the trephination procedure, a small supraorbital incision is made below the medial eyebrow and the underlying periosteum is elevated. A bore hole is then made through the skull bone and into the sinus cavity. The interior or the sinus may then be cleaned and small tubes may be inserted and used for future irrigation or drainage. In some cases, trephination may be performed concurrently with endoscopic frontal sinus surgery. In some patients, the intersinus septum may be removed and a single opening may be created through which both frontal sinuses may drain into the nasal cavity. The main contraindication to the trephination procedure is the presence of an aplastic frontal sinus.
Other open surgeries, known generally as frontoethmoidectomies, have also been used to treat frontal sinusitis and associated ethmoid disease. These procedures have been performed by various approaches, including those known as the Lynch approach, the Killian method, the Reidel method and the Lathrop or Chaput-Meyer approach.
Another group of open procedures used to treat frontal sinusitis are known generally as osteoplastic flap procedures. These osteoplastic flap procedures are typically employed only in severe cases where frontal sinusitis is refractory or accompanied by intracranial complications. Osteoplastic flap procedures have been performed by various approaches, including a coronal approach, a midline forehead approach and a brow incision approach. After an initial incision is made by one of these three approaches, a template may be used to outline the frontal sinus. An incision is then made through the periosteum at a location slightly above the outline of the sinus. The periostium is elevated and a saw is used to cut into the frontal sinus. Small cuts may also be made above the glabella to loosen the frontonasal suture. In this manner, an osteomeatal flap is created, exposing the interior of the frontal sinus. The surgeon may then remove the diseased sinus mucosa and may also alter the structure of the sinus and/or FOT, such as by removal of the intersinus septum. The remaining frontal sinus cavity is then packed with autogenous fat or other materials (Gelfoam, Teflon, fat, paraffin, silastic sponge, and cartilage), the osteomeatal flap is replaced and the periostium and skin layers are then closed with sutures. Some modified versions of the osteoplastic flap procedure also include the use of a pericranial flaps and/or cancellous bone grafts.
In general, open surgical procedures do provide excellent visualization of the interior of the sinus, thereby enabling the surgeon to see and correct a variety of problems. However, these open procedures can be extremely invasive. They also result in at least some visible scarring and typically involve substantial obliteration of existing anatomy to create an open frontonasal communication.
The prior art has included some disclosure of the use of balloon catheters to dilate anatomical passages and improve drainage from paranasal sinuses. For example, U.S. Pat. No. 2,525,183 (Robison) discloses an inflatable pressure device which can be inserted following sinus surgery and inflated within the sinus. Also, United States Patent Publication No. 2004/0064150 Al (Becker), now U.S. Pat. No. 8,317,816, issued on Nov. 27, 2012, discloses balloon catheters wherein a balloon is mounted on a stiff hypotube that may purportedly be pushed into a sinus. The stiff hypotube has a fixed pre-set curve or angle. Additionally, an abstract entitled Balloon Dilatation of Recurrent Ostial Occlusion of the Frontal Sinus, by D. Gottmann, M. Strohm, E.-P. Strecker and D. E. Karlsruhe describes balloon dilatation of recurrent ostial occlusion of the frontal sinus in seven patients suffering from recurring chronic frontal sinusitis who had undergone between two and four prior surgeries for the condition. Using endonasal access the ostium of the frontal sinus was crossed with an angiographic catheter and a hydrophilic guidewire under fluoroscopic control. Then, the stenosed ostium was dilated with a high pressure percutaneous transluminal angioplasty balloon having a deflated diameter of 5 mm and an inflated diameter of 8 mm. This procedure was performed 2 to 8 times in each patient, at intervals of 2 to 12 weeks. The abstract reports that all of these procedures were technically successful and there were no complications. Although the prior art does disclose some uses of balloons to dilate the ostia of paranasal sinuses, the prior art has not disclosed specifically sized or configured balloons or other dilators that may be used to dilate the entire length of a FOT (i.e., the frontal sinus ostium as well as an adjacent frontal recess) in a single step or without the need for repositioning and multiple inflations of the balloon.
Because the surgical treatments for frontal sinusitis are invasive and associated with various risks and complications, there remains a need for the development of new devices and techniques for treatment of frontal sinusitis with less trauma and less risk of complications. Also, since surgical treatments for frontal sinusitis are typically reserved for only severe or refractory cases, there remains a need for the development of new interventions that go beyond the previously available conservative treatments (e.g., medical therapy with antibiotics, steroids, mucolytics, saline lavage, etc.) but do not involve the tissue trauma.